Potassium zeolites



`Patented Nov. 1l, 1952 BQTASSIUM ZEOLI'IESA George R. Bond, Jr., Paulsboro., N; l., assigner 'tgf 'Houdry Processu Corporation, Wilmington,r Del.l,ja corporation ofi'Delaware i Nacomwing; Atpiicationmnels, inaA 'ScriakNw 100,980.l

The-present inventionrelates to .contact masses anidtheir preparation-,r'r1fore particularly y it is concernedl Withthe production and'treatinent of caters by wet methods.

A tlciallzeolitesp fparedgby reaction of soluble. silicates.; with aluminum; COmDOfidSOf "other inorganicicornpoundsfhaye found Wide usein the treatin befreien @nii-forL Other-@weies Where-v in; therese exchanging Capacity f` the 2201i@ 'is utilized. The. known; materiels onvilimlv in-useror this purpose, l andparticularly artificially prepared siiceous exchangel materials such as Zeolites, are duiteffriable'in-dry stateorlose a considerable portionof, their @Xchange capacity on heating to even' moderate calcination temperatures. "l"

Ifhavefound; that, inorganic base exchange siliceousmaterials', such as; zeolitescomprising hydrosil'icate" of alur'nin'um,v containingV potassium inbastex'change position' can'be hea'te'd toeleya't--- ed temperatures sufficient to xf the structure of the" materials; 'imparting' hardnesstheretowhile retaining tdapredominant extent'their exchange capacity.` In accordance'fwith; the invention', a technique is provided for thel manufacture of ruggedhigh capacity. material'for base exchang-v ing purposes; such 'as water softening, or purifica'- tionl off sugar solutions, etc.,"whi c h; material is largely 'freeffromdefects oft previouslyf used'v zeolitic materials ofthis class,` 'Ijheinvolyedtechnique, moreoverl is applicable to the preparation offgcontact masses for use iii-operations other than: thosey primarily; associated-f with; i911. @K change, such siliceouscatalysts.

In. accordance with the invention; a baserex- Change mass: comprising VSilica;` and# alumina is prepared .contamina potassium in. bascrexbane@ position? and; the is 2i1cir1eiv at a temperature in) excess Q f 599; E? tQ the; Structure-fof the mass, thereby rempvas a c. t associated.v The 'caminata mass: @an '11F-1G11 be directly; employed in; known manner, fQr: Sofienins of Water or other; uuriiicatmn-,Oiiuids-by ion exc.bange and is capable; 0i; regeneration.' in oust cmary.` manner byw removal of'y contaminar ing ionsfthusj taken up, with solutions containing," ammonium, hydronium or alkali metal` ions.

The high temperature stability of the potassium-containingaluminurng silicates; Wasi not lto be expected; inview oi the known belilaviourV of corresponding z'eolites containngsodignm. Thus, inthegpreparation of 'Siliceous catalysts toghe em- DlOyedin high temperaiuire. contacting reacticris, such: as catalysts for: hydrocarbon. cQIivcrSiOr-,l 1i@- se part of the Whenfused at ytl'ierequireol elevated temperatures, The uxing action of allgalijmetalsalts on siliceous and other minerals being known; itis commonly believed that the loss inactivity demonstratedin connection with theuse o f silica-aluminaly catalyst containingy sodium; is associated With ,th-is. uxing action; the inactivity being perhaps occasioned-inpart ,atleast by sintering and shrinking ofy the catalyst v'vithjconsequent loss in adsorptivecapacity'. In the production of sodium-free catalyst, therefore, itl hasV been the'practice inthe art toreinove the sodium content down tov a. practical insignicant residual quantity prior tothe use ofI the" catalyst at elevated teinperatures encountered in `a`hydrocarbon conversion operation,"or priorto ajprepalaiory calcining operation designed to iixV the structureA and/or activityof the catalyst., Such removalv of sodium is accomplishedVy by J., R. Bates'inthe U. S. Patent 2;283`,172, by exchanging the sodi,- um under selected conditions by avolatile' or o decomposable cation, so' that the obtained zeolite can be y subjected toheat, treatment at required temperature to drive off,the?volatile cation'and yieldja catalytic product consisting essentially of the nucleusiof. the zeolit'e.

While the ammonium-containing zeolites, such as those ofi theBatespatentfreferred' to, do not shrinkr on heating to. high temperature tothe extent exhibited by the corresponding sodiumcontai-ning products, these" ammonium zeolites l nevertheless rapidly. lose a major portionoi` their exchange capacity when subjected. tov temperatures effecting. evolution. off exchangeably held ammonia. therefrom." The potassium-containing zeolites; on: the4 other hand,`riot onlyv shrinljtc .4 aiconsiderabiy lesser extent thatjthe correspondingsodium-containing pr`od uctsv but retain. their actions; the removal ci? sodiurnassociated in they l exchange capacity after calinationftoa remarkably higher extent thanj'either the sodium or ammonium zeolites, 'Thepotassiuin Zeolitesfrei taintheir ba's'e exchange capacity to satisfactory extent evenafter heating to eenige as 14cm F., and retain up to about' 90% ofl theirexchange capacity ywhen heated under the same conditions that corresponding ammonium products have only 10 %of originalcapacity'. Lioreover; the cal',- cinedpotassium z'eolit'e"s"`not only "cani be'substantially completely `reexchanged with desired cationsl such as metal, cations",` 4amrnoiiiurn` and hydmniu'm, but indie Case` of, re henger-111:11

ammonium` demonstrate a. surprising increase, in.

thermal stability" Cf, "the meente.' Thus, a calcine'dl potassium-containing, silicaalumina gely reexc'hangedfuiithf ainrnoni in, heated at'y '950 FQ for' "approximately hours,

@vowed only about hair of; itsammciua instead.v of the expected! evolution of amnfivonia.A f i Since the calcined potassiumzeolite hasa desirable hiermee@ epa' ,fr 'and' retains iis structural form in contact with aqueous liquids; formed bodies such as granules, lumps, or regularly shaped masses of such potassium zeolites, such as tablets or pellets, can be prepared and then calcined, and the potassium in the calcined bodies subsequently exchanged by other desired cations through treatment with aqueous solutions comprising such desired cations. Thus a silica-alumina gel or precipitate containing potassium may be calcined and the calcined mass then treated with solutions of acids or ammonium salt solutions, or with solutions of salts such as those of chromium, magnesium, beryllium, zirconium, or other metals desired to be incorporated in the preparation of catalysts or contact masses for other uses.

For incorporation of controlled limited amounts of metallic or other cations in the zeolitic mass less than the base exchange capacity of such mass, as may be desired in the preparation of catalysts or the incorporation therein of promoters or other cations conferring certain desired properties to a catalytically active zeolitic mass, an eicient and readily controllable procedure is provided. Thus a freshly prepared siliceous zeolitic gel or precipitate containing sodium as contaminant may be treated with ammonium salt solution to free the same of sodium, and the resulting ammonium containing zeolite then treated with a potassium salt solution containing that quantity of potassium stoichiometrically equivalent to the quantity of metallic cation desired to be incorporated. The gel can then be heated to drive off the remaining ammonia. Subsequent treatment of the gel with a solution of metal salt containing the desired cation will effect ready replacement of the potassium in the baseexchange positions by the desired metal cation, while the positions previously occupied by ammonium will be substantially unaffected.

The silica-alumina zeolite may be prepared as a gel or precipitate in known manner, for instance by reaction of alkali metal silicate and an aluminum salt. Potassium may be exchanged for other alkali metal ions present in the zeolitic gel or precipitate, before or after drying of the same, but prior to subjecting the gel or precipitate to elevated temperatures, such as above about 400 F. Because of their ready availability and low cost; commercial sodium silicates are desirable raw materials for use in preparation of siliceous products.

In a typical procedure, the fresh wet silicaalumina gel or gelatinous precipitate containing sodium (as a result of preparation from sodium silicate), is permitted to drain and/or undergo syneresis, then is partially dried, and Water washed. Removal of exchangeably held sodium may then be effected by treatment with ammonium salts as described, for instance, in Bates U. S. Patent 2,283,172, or directly by treatment with potassium salt solutions. If ammonium exchange is employed, the ammonium may then be replaced entirely or to desired extent by potassium, the remaining non-exchanged ammonium being largely volatillized in subsequent calcination. Such exchange of ammonium by potassium may be performed before or after the zeolite has been shaped in pieces of desired size and form. For instance, the ammonium zeolite may be washed and dried; then made into a paste by addition of Water or wet gel to obtain the desired consistency for forming of tablets or pellets by molding, extruding or other shaping operations. The pellets are then dried at. a tem- F4 perature below about 250 F. The dried pellets may then be base-exchanged to incorporate potassium and calcined at 800-1400 F.

The calcined pellets Ythus obtained can be employed directly as a water-softening and purifying agent. If a hydrogen-treated zeolite is desired, the potassium may be further exchanged cr removed as by treatment with formic, acetic, or dilute mineral acid; or can be further exchanged with ammonium ions and heated to drive 01T NH3.

The potassium zeolites may be prepared in the form of spheroidal beads, employing known methods, such as those generally described in the U. S. patents to Marisic, of which U. S. Patents Nos. 2,335,217 and 2,384,946 are typical. Thus, a silica-alumina hydrosol containing sodium may be admitted to an immiscible liquid to form globules of desired size, and the globules set to a rm gel in the immiscible liquid. The spheroidal hydrogel beads thus obtained may then be treated in Wet state to substitute the sodium by potassium, or removal of sodium may be effected by treatment with ammonium salt solutions and the ammonium replaced by potassium to desired extent before or after the gel beads have been dried. The potassium-containing beads may then be calcined.

EXAMPLE I A. A silica-alumina zeolite was prepared from a solution of commercial water glass containing by weight about 8.9% NazO and 28.5% SiOz, and a solution of sodium aluminate in proportions giving a weight ratio of SiO2/Al203 of 87.5 to 12.5. Each of the solutions was diluted with water and the diluted solutions rapidly admixed in the presence of ammonium sulfate solution furnishing sulfate anion equal to about the stoichiometric equivalent of the total alkali metal content of the silicate and aluminate solutions, with the formation of a coagulum having a pH of approximately 9.7 and containing about 3.9% by weight of Na (water washed and dried basis). The product was steamed, dried at 240 to 260 F. and coarse ground. The coarse granules were treated in a counter-current system with ammonium nitrate solution and with water to remove sodium, and the product freed of excess water on a filter press. One-third of the filter cake was dried (at about 240 F.) and pulverized, then mulled with the remaining wet filter cake to form a paste which was molded into cylindrical pellets of 4 millimeter diameter and length, and the pellets dried at about 220-240 F.

The dried pellets Which now contained 3.14% NH3 (analysis after storage) were treated in different batches as follows:

B. The dried ammonia-containing pellets were treated with 15 aqueous potassium nitrate solution, resulting in the incorporation therein of potassium equal to 8.21% KzO by weight of the pellets;

(a) One portion of the pellets from B above was heat-treated at 1400 F. for 10 hours in 95% air-5 steam, then tested as a catalyst in cracking of a gas oil under standard conditions; only an insignicant gasoline yield was obtained.

(b) The potassium in the catalyst of (a) above after regeneration to burn off coke, was partially exchanged by hydrogen through treatment with 5% forrnic acid; the acid-treated pellets contained 4.12% KzO. These pellets were tested as a polymerization catalyst on isobutylene at 46o-490 F., resulting in the formation of 45.1%

asuma by. vWeight liquid productl containing, 47.4% by weight of; dimer (Go-hydrocarbons);. in a..- subsequent run; at1460 F., .af ter regeneration -of.v the catalyst from:V the vfirst polymer-ization run; there containing 58;9%1` dimer in-` thefliquid, producing.

2.8% coke-by Weight ofV charge in the z-run.

(c) Another portion of the potassium-exchanged catalyst from Bfabove-wasfheatf treated at.;-10,50 F; .for, 2 hoursfgand --testedigforf cracking activity -onfgas yoil onlypan linsigniicantfamount off` th-eoil;charge;'.Wasf4 cracked.r

(ur. Tempeliers-nimm 01 i above; aftergref. generation;to:` --burn oilcokejl deposit from@` the previous cracking run were partially exchanged.

withammonium chloride solution, incorporating 2.7%; ammonia, (theg pellets contained 0.66%; re-` sidual KZO). One portionrofgthe--pellets-Wasrthen` givenv a static, heattreatmentgin its; own.; evolved proximately;3 other portion-Z of. thef-ammonium-exchangedj pelletsfwasfheated. in;l flowing air j at .approximately 1400?" F-.f resulting .inevaporation rof Vthepamrrn'iriiato'.v afresidual` content inther pellets ,of 0.03%,

These-pellets gemployedfin; .cracking of vthelight gas oil 1unde1',"the.same;-.conditionfasvthe previous catalyst" gave agyieldof approximately 38%; gasoline by volume of theycharge.4

The; abovetestsindieate; that the cracking activity ofV `the catalyst is retained after; calcination. of." the potassium-containing 'zeolite-l and vsubse-` quent removaloff potassium.

EXAMPLE *II* Anotherv batch: of. silica .alumina pellets. pre;-

pared-similarly. to the. product described under (A) of Example I above, Was-analyzed; the dried pelletscontaining 3.3%` NH3. y

A.- The above ammonium-containing` pellets were treated With..15%. aqueous potassium chloride solution, (150 grams KCl per. liter ofv solution). thereby removing-NH3 from the pellets by' replacementwith potassium to residual content` of 0.21 ammoniabeing retained. The produ-ct.

was `heat treatedfat1050f for 2 hours in flowing air. and thendividedinto. a-number of portions whicnwerevariously treated to determine the retention of base exchange properties, as fol'-` loWs:

(a) Oneiportionof the potassiumfcontaining pelletswas treated., with acetic. acidwith. the.y

resulting; removal' of 36%,vv of thepotassium 'content.

(b) Another portion of the above potassiumcontainingpelletsy was treated With formic acid resulting in the removal of about of the potassium content..

(c) Another'portion ofthe potassium containing pellets from (A) abovefwastreated with-15% ammonium chloride solution with Ythe resulting demonstrated. .by altern reexchangetwith.ammoniumchloride resultedV in pellets having. 2L8?.%I.NII3.. The. last.. described pellets were .again .reexfchanged with potassium with. the resulting deposition of6 .50 KzO which Was,` againreplaced. byammoniumY exchange to.,v a

content:of.2. 86.% NH3..v

lTo ,establishj dii'erencesfin the behavior. of po.-

tassium andsodiuminzeolites ofths typea sili-` oa-.alumina gelcontaining ammonium. from. the` puricationtreatment yinlremoval of sodium, was

prepared in-pelletform and` dried at a temperature below 250 F.; theammonia containing. pellets were then treated with v15% sodium chloride solution to replace-ammonia Exhaustive treatmentilowered.the;residualcontentto` 0.66% NH3 by'vveightV of; pelletauas;` compared` with ready andi'neallyfcomplete; replacement of NH4` by potassium The comparativeresultsare. tabulated below.:-

Table 1` M0181 Total 'Residual Treating sol'n.A Conc., Molsr vNH3 in i Mols/1;; Used.4 Pellets Percent; l. 65v 3. 9 0. 18 1. 00 5. 4 0. 05 2. 56' 5.` 3i 1136 2.56. 21.7 0.66

l steam underwent asevera-shrinkage in Volume of over 40% and a corresponding increase in bulk density.from,0;5,l to 0:78 kilogram per liter; as compared with the lpotassium-containing pellets which shrank under the same heat treatment about 25%.t'o less than 30% by volume,` With a corresponding increase. in bulk density to about 0.6 kilogram per liter.

The heat treated sodium-containing pellets were then. treated with ammoniumV chloride solution with the resulting desposition of 1.13% NH3. This is equivalentxto a theoreticalremovalof only 38.5% o f thesodium present in the1 heat treated pellets, ,and is n sharp, contrast to the correspending, -9.Q%.retenb0n ofibase exchange 'capecity- Off? the: Celcinedi potassiumretaiiline pellets The reexchanged ammonia-containingr pellets were. again. heat-treated as before, at; 1400?'11. for, 10; hoursin 5%;Stoa-.n nundergoingY an additional' 6%, volume shrinkage.. 'I ested for cracking. off a lightgas oil under the same, conditions asthepreviousvtfests thiscatalyst gave a'A yield of only. about `21-22%..gasoline as compared' tothe 4.3%. gasolme` obtained. for the similarly treated potassiurra-excl;angedcatalyst, v

In the. ioregongV examples, the standard catalytic. cracking activity tests referred to were carried ou.t.u:o dery the conditions described in Haber,atorvr Method fer. Determining, the. .Activity of'Cracking Catalystsby J .,Alexandler, and H'. G.

te, exchangey withv por. tassiux'n .andlammonium ions.` as.: follows z treat'-. ment ofythep pellets.containing.` 2.84%; NHa with. 15%,-.potassiumi-vchloride solution resulting in a.. deposition Lot potassium equal'- t'o 6.34% KzO. and' Shimp, National Petroleum News, Technical Section, August 2, 1944, at pages R-537 and R538. In accordance with the described method, Aa light East Texas gas oil is contacted with the catalyst ata temperature of approximately 800 F. under super-atmospheric pressure and at a liquid space rate of 1.5 (volume charge/volume of catalyst/per hour) for a ten minute operation period. The volume of gasoline of 410 F. cut point is measured and expressed as a percentage of the Volume of oil charged, thereby designating the characteristic activity of the catalyst. In addition, the quantity of carbonaceous deposit formed in thecatalyst is also usuallymeasured and expressed in terms of weight percent of charge, and the specific gravity and weight percent 'of gas produced is also determined. Y

EXAMPLE In liters of water passed through were at zero hardness. Regeneration of the zeolite with potassium chloride solution and analysis of the eiiiuent showed the removal by the zeolite of more calcium and magnesium from the water than that accounted for in the decreased hardness shown on titration, and corresponded to an equivalent Value of approximately .07 gram per liter calcium carbonate removed. Evaporation of the tapV water sample showed the presence of 1160 parts per million of salt which may be responsible in large measure for the'low values obtained by titration methods. For more eiicient softening in practical use of the zeolites, a deeper bed should be employed than that of the above test.

EXAMPLE IV A silica-alumina hydrogel is prepared from alkali-metal silicate and an aluminum compound following the procedure of Example I paragraph A, above. Removal of sodium by exchange with ammonium salt solution may be carried out before or after pelleting of the product but prior to calcination. The ammonium zeolite thus obtained, after washing and low temperature drying, is treated with 0.75% aqueous KCl solution (7.5 grams KCl per liter of solution) under agitation of the treating solution and in approximately the proportions of two liters of solution per kilogram of the zeolite. Under these conditions about 0.7 to 0.8% potassium are deposited in the zeolite, replacing the corresponding equivalent of ammonium ions.

The potassium-containing product is then washed and dried (and pelleted if not already in pellet form), and the pellets then heat-treated in iiowing air at 100G-1200 F., thereby driving off ammonia, while retaining the base exchange capacity to substantially the extent` of the potassium content. The pellets are then treated with a manganous salt solution in excess of the equivalent potassium content of the pellets (such as above 18 grams MnCl2-4H2O per kilogram of initial ammonium zeolite), which treatment can be eiected by percolation, immersion or any desired manner. The manganese treated pellets are then Washed and dried.

The catalyst thus prepared contains 0.5% manganese as a regeneration accelerator.

Obviously many modifications and variations of the invention as hereinbefore set forth may be made without departing from the spirit and scope thereof and therefore only such limitations should be imposed as are indicated in the appended claims.

I claim as my invention:

1. The method of preparing a hydrogen-ion exchange material of improved stability which comprises calcining a potassium containing siliceous gel zeolite at a temperature of 800-1400 F., and substituting hydrogen for potassium in the zeolite.

2.-The method in accordance with claim 1 wherein the substitution of hydrogen for potassium is effected by acid treatment.

3. The method of preparing a contact mass which comprises calcining a potassium-containing siliceous gel zeolite at a temperature of 800-1400 F., treating the calcined potassiumcontaining zeolite with an' ammonium salt solution to incorporate ammonium in said zeolite by base-exchange, and thereafter heating the resulting product to volatilize ammonia therefrom.

e 4. The method of preparing a contact mass which comprises the steps of forming a hydrogel comprising silica and alumina and containing sodium as contaminant, removing sodium by treatment with an ammonium salt solution, replacing the ammonium in said gel atleast in part by potassium ions, and calcining the potassiumcontaining product at 8001400 F.

5. The method in accordance with claim 4 wherein the ammonium in the gel is replaced only in part and in predetermined amount by potassium so that on subsequent calcination ammonium is volatilized to produce a product of desired potassium content, which content is readily replaceable by base-exchange with catalytically active metal ions in substantially stoichiometric amount.

6. The method which comprises reacting sodium silicate and an aluminum compound to form a sodium-containing zeolite, drying the product, removing sodium therefrom by baseexchange with an ammonium salt solution, pelleting the obtained ammonium zeolite, drying the pellets, base-exchanging potassium to replace ammonium in said pellets by treatment of the dried pellets with a potassium salt solution, and calcining the potassium-containing pellets at 800 to 1400 F.

7. The method of claim 6 including the further step of replacing potassium in the calcined pellets by base-exchange with desired cations selected from the group consisting of ammonium, hydronium, and metal cations.

GEORGE R. BOND, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

6. THE METHOD WHICH COMPRISES REACTING SODIUM SILICATE AND AN ALUMINUM COMPOUND TO FORM A SODIUM-CONTAINING ZEOLITE, DRYING THE PRODUCT, REMOVING SODIUM THEREFROM HY BASEEXCHANGE WITH AN AMMONIUM SALT SOLUTION, PELLETING THE OBTAINED AMMONIUM ZEOLITE, DRYING THE PELLETS, BASE-EXCHANGING POTASSIUM TO REPLACE AMMONIUM IN SAID PELLETS BY TREATMENT OF THE DRIED PELLETS WITH A POTASSIUM SALT SOLUTION, AND CALCINING THE POTASSIUM-CONTAINING PELLETS AT 800* TO 1400* F. 